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Re: Lag Bolt Zperp values in thin members

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Jordan,
As a little bit of an aside, what do you do about 
bolting to or through a brick veneer. I received a
second inquiry in two years, this week about a deck
ledger bolted through brick to the rim board; both
times it has been a government official. My position
has been that there is nothing in our code that forbids
bolting to or thru brick.  I don't like bolting directly
and only to a brick veneer, but there are thousands of
home-made decks out there with this manner of connection
without any known problems. TIA
Gary

On 20 Apr 2006 at 8:37, Jordan Truesdell, PE wrote:

> I've just run across an interesting table in the Virginia version of 
> the 2003IRC, and wonder what others thoughts are on the matter. The 
> table in question is R502.2.1.1 (you can see the VA table here ) and 
> it gives ledger lag spacing for deck connections to residential 
> construction. If you back calculate the spans, you get 375# per 1/2" 
> lag. For example: 
> 
> 12' deck joist span, 
> 50psf TL (10D/40L I'm assuming), 
> 1/2" diameter lag screw through a 
>  2x S. Pine ledger and 
>  2x solid sawn rim joist (no species provided, SPF is the most 
> common solid sawn rim material)
> so 12'/2 (trib) x 1' x 50psf = 300#/ft
> 
> For a 12' span, the table requires a 1/2" dia. lag on 15" centers. So 
> 300#/ft x 1.25' = 375#. 
> 
> That's all well and good, except that according to the 2001NDS: 
> 
> 1) a single shear connection for a 1/2" lag for a 1.5" side member 
> when loaded perpendicular to the grain is 250# when the penetration 
> into the main member is 8x the lag diameter, or 4". and
> 
> 2) The minimum penetration is supposed to be 4D, which you cannot 
> have with 2x lumber, even if you count the sheathing (7/16"+1.5" < 
> 2").Even at the minimum penetration of 2", the allowable shear value 
> is only 125#. 
> 
> 3) The table value I gave was for S.Pine/S.Pine., for SPF the value 
> drops by 25%. 
> 
> Stranger yet, the values for through bolts are nearly double (29" vs 
> 15") at the 12' deck span. 725# for a single 1/2" through bolt? NDS 
> gives 330# for 1-1/2" to 1-1/2" w/ side member loaded perp to grain.
> 
> I hadn't taken the time to calc out these numbers until this morning, 
> when I got a call on the ledger attachment for a deck with a hot 
> tub.I assumed that lags couldn't be used with the tabulated values, 
> but that the VA code officials had a specific analysis done for the 
> short penetration. Looking at the table more closely, the numbers 
> make no sense. I haven't seen a mention anywhere of the values 
> determined through testing. Am I missing something technical here?
> 
> Thanks to those who made it this far. 
> 
> -- 
> Jordan
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